There is increasing concern over the development of resistance to available chemical pesticides by mosquitoes and other insects of medical importance. Insect pathogenic viruses, specifically baculoviruses, have characteristics which suit them for use in integrated control programs. Baculovirus pesticides must be characterized as a quality control measure to ensure the correctness of their label and to detect possible contaminating viruses. Since the viruses are produced in insects which are not necessarily from virus-free colonies, there is a hypothetical risk of contamination. The baculovirus insecticides are sprayed in the environment; identification of both the pesticide itself and the baculoviruses that may be recovered from non-target organisms is necessary to evaluate possible untoward effects of spraying. Baculoviruses have supercoiled, double-stranded DNA which may be subject to possible recombination during the insecticide manufacturing or in the environment. The analysis of baculoviruses by genetic characterization of mutants and of recombinants will provide tools for the study of the viral pathogenesis in insects; and the detection of the oncogenic, the teratogenic, and the mutagenic potential of the virus in vertebrates. This proposed study to characterize the baculovirus genome provides the basis for the understanding the nature of virus-host interactions and virulence, and it developes a technology for evaluating and improving potency, purity, safety, and efficacy of baculovirus pesticides. After viral genes are correlated with their functional gene products, then these findings would be applicable to virus production, field efficacy, and environmental safety problems.